This invention relates to a flange, made from material of rubber-like elasticity, having an outer and an inner peripheral sealing surface, as well as an apparatus for producing enveloping casts about elongated bodies, wherein the body to be enveloped is positioned coaxially in a tube which together with two terminal closures, forms an annular chamber about the body, into which a liquified casting mass is introduced via one of the two terminal closures.
Flanges having external and internal sealing surfaces are mostly employed as terminal closing means for molds used to produce enveloping casts about elongated bodies, and particularly about pipes.
For this purpose, the pipe to be enveloped by a cast is arranged concentrically within a pipe of larger diameter, and the annular space thus provided between the pipes is hermetically closed by a flange, at least at one of its ends. The mass of casting substance is introduced into the mold either via inlet openings in the peripheral wall of the external pipe, or via axial bores in the flange. The first-named kind of introduction, which will be designated as the radial one hereinafter, has been employed, for instance, in the devices known from the U.S. Pat. Nos. 2,730,769; 2,177,221; 2,129,680 and 3,307,590. The second kind, which shall be designated hereinafter as the axial one, has been embodied in a device known from U.S. Pat. No. 3,941,531.
The radial introduction of the casting mass leads, naturally, to strong turbulences and occlusions of air. It is therefore unsuited for the processing of the more highly reactive casting resin masses, in particular foamable synthetic resin masses. (When processing thermoplastic casting masses, occlusions of air are not such a problem because occluded hollow spaces can be eliminated by re-melting the surrounding portion of the cast mass.)
In accordance with U.S. Pat. No. 3,941,531, an axial introduction of the casting mass is carried out via several bores or tubulures arranged concentrically in a circle. This, however, does not afford a sufficient freedom from turbulence. Therefore, this arrangement cannot be used either in processing masses of the more highly reactive casting resins, especially of foamed plastics except within relatively narrow limits. A further drawback of the device of U.S. Pat. No. 3,941,531 is seen in the relatively long pipe conduits which can be cleaned only with difficulty or not at all.